Storage system

ABSTRACT

In a RAID system, the power supplied to hard disks (HDDs) can be increased, and a plurality of types of HDDs can be installed. A plurality of HDD packs  33  are supplied with a single high voltage from a motherboard  28 . The HDD packs  33  each accommodate, in a canister, an HDD  107, 181, 185  or  187  with different power supply specifications or communication interface specifications, as well as a DC/DC converter  109  to convert the power supply. Part of the HDD packs  33  have a data transfer interface conversion circuit  195  as well.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.10/802,913, filed Mar. 18, 2004; which claims priority from JapanesePatent Application No. 2003-428829 filed on Dec. 25, 2003, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a storage system having a plurality ofphysical storage devices (for example, hard disk drives), and inparticular to technology to provide a power supply to a plurality ofstorage devices.

2. Description of the Related Art

Storage systems of which RAID systems are representative comprisenumerous storage devices, such as for example hard disk drives(hereafter abbreviated “HDD”). In Japanese Patent Laid-open 4-78062, aRAID system configured to supply power to a plurality of HDDs from thesame power supply circuit is described.

In general, each of the HDDs installed in such a storage system isassembled as a single unit (hereafter called a “HDD unit”) in which thegroup of components necessary to function as an HDD (for example, themagnetic disks, read/write heads, power transmission mechanisms andother mechanical components, the motors and other electromechanicalcomponents needed to drive the former, and the driver circuits for theelectromechanical components, logic circuits for data processing,microprocessors, and other electrical circuit components) areindivisibly integrated and fixed in a single casing. An HDD unit hasconnectors for connection to data communication circuits within thestorage system and to power supply circuits. The physical specificationsof the connectors are characteristic of the specifications of theinterface for data transfer adopted by the HDD; typically, an HDD unithas a prescribed plurality of data transfer terminals and a prescribedplurality of power supply terminals. There are various electricalcircuit components within an HDD unit, and different types of circuitcomponents require power supplies at different voltage levels. Forexample, logic circuits for data communication and control require a 5V_DC power supply, whereas motors, heads, and other actuators require a12 V_DC power supply. A plurality of power supply terminals among theconnectors are allocated to such power supplies with different voltagelevels.

Efforts are made each year to expand the capacity of this type ofstorage system, and the number of HDD units installed increasessteadily. In addition, higher reliability, more compact size, and lowerprices are also sought. Further, as magnetic disks move toward higherdensities, faster data transfer rates and higher revolution rates, thereis a trend toward increased power consumption within HDD units. On theother hand, there is also a trend towards diversification of thespecifications of power supplied to HDD units within a storage system.Also, there is a trend toward adoption of interface specifications fordata transfer to HDD units enabling faster operation and lower prices,such as for example the Small Computer System Interface (hereafterabbreviated to “SCSI”), Fiber Channel Interface (hereafter “FC”), andSerial ATA (hereafter “SATA”).

Given the above circumstances, there are the following problems anddemands.

(1) The number of power supply terminals of the connector of an HDD unitis fixed at a certain number by the specifications of the interface fordata transfer, and there is a constant upper limit to the current whichcan flow to each power supply terminal. For example, FC specificationsstipulate that a connector has four power supply terminals, and that theupper limit to current which can flow through one power supply terminalis 1A. Normally, two power supply terminals are allocated for 12 V_DC,and two power supply terminals for 5 V_DC. Hence only current up to 2Acan be supplied to an HDD unit by either a 12 V_DC or a 5 V_DC powersupply. However, as explained above, there is a tendency towardincreases in the power consumption of HDD units, and so there is thepossibility that it will no longer be possible to supply adequate powerto HDD units using existing power supply terminals.

(2) The trends in recent years toward increases in the number ofinstalled HDD units and toward increasing HDD internal power consumptionhave given rise to the need for larger-capacity power supply circuitsfor storage systems.

(3) In addition to existing HDD units requiring supply of a plurality ofvoltage levels such as 5 V_DC and 12 V_DC, HDD units which require thesupply of other voltage levels are appearing. Consequently it isdesirable that a single storage system be able to accept installation ofa plurality of types of HDD units with different power supplyspecifications.

(4) There exist a plurality of various specifications for the interfacefor HDD unit data transfer, such as for example FC and SATA. Hence it isdesirable that a single system be able to accept installation of aplurality of types of HDD units with different interface specifications.

SUMMARY OF THE INVENTION

Hence an object of this invention is to increase the power that can besupplied to the HDD units installed in a storage system.

A further object of this invention is to enable installation of aplurality of types of HDD units with different power supplyspecifications in the same storage system.

Still a further object of this invention is to enable installation of aplurality of types of HDD units with different interface specificationsin the same storage system.

In order to achieve the above objects, a storage system connectable to ahost computer according to one aspect of the invention disclosed in thisapplication comprises a plurality of storage devices which store datafrom the host, a plurality of housings in which the plurality of storagedevices are respectively mounted, and a plurality of first powersupplies which supply a voltage to the plurality of storage devices. Atleast one among the above plurality of housings has a voltage converter;this voltage converter receives power having a first voltage value fromthe above first power supply, converts this first voltage value into adifferent second voltage value, and supplies power having a singlevoltage value to the storage device.

A storage system according to another aspect of the invention disclosedin this application comprises a plurality of physical storage devices(for example, hard disk drives), and a power supply circuit whichoutputs power at a prescribed voltage level. Power conversion circuitsare provided for each of the physical storage devices, and each powerconversion circuit converts power at the prescribed voltage level fromthe power supply circuit into power at the voltage levels required bythe corresponding physical storage devices, and provides the power tothe physical storage devices. By selecting the output voltage level ofthe power conversion circuit for each physical storage device, aplurality of types of physical storage devices having different voltagespecifications can be installed in the same storage system. It isdesirable that the voltage level output by the power supply circuit be asingle level equal to or greater than the highest level among the powersupply voltage levels required by the plurality of physical storagedevices. When the internal circuit components of a certain physicalstorage device require a plurality of types of power at differentvoltage levels, the power conversion circuit for that physical storagedevice may output all the plurality of types of power at the differentvoltage levels, or may output a single type of power at the highestvoltage level (or at a voltage level higher than the highest voltagelevel) among the plurality of types of power. In the latter case, it isnecessary to perform power conversion within the physical storage deviceof the voltage level from the power conversion circuit to the lowervoltage levels required by the internal circuit components. However,because the voltage applied to the physical storage device is higher,the current flowing to the power supply terminals in the connector ofthe physical storage device is smaller, and so the power which can besupplied within the range of allowable currents of the power supplyterminals is increased. Further, when one type of power is supplied to aphysical storage device from a power conversion circuit, if theconnector of the physical storage device has a plurality of power supplyterminals, all of the plurality of power supply terminals can be usedfor the supply of the one type of power. As a result, higher power caneasily be supplied within the range of allowable currents of the powersupply terminals.

In a method of power supply to a plurality of physical storage devicesaccording to a further other aspect of the invention, power is generatedwith a prescribed voltage level, and power at this prescribed voltagelevel is converted into power at the voltage levels required by therespective physical storage devices and is supplied to the respectivephysical storage devices.

A storage system according to a further other aspect of the inventioncomprises a power supply circuit which outputs a single type of powerhaving a single voltage level; a main body having a main power supplyline to send the one type of power output from the power supply circuit,a data transfer path for data transfer, and a plurality of packconnection sites; and a plurality of storage device packs which canreceive the above one type of power from the main power supply line, canexchange data with the data transfer path, are respective connected tothe plurality of pack connection sites of the main body, and can beremoved from the pack connection sites. Each storage device pack has aphysical storage device requiring supply of power of one or more typeswith prescribed voltage levels and a power conversion circuit whichreceives the one type of power from the above main power supply line,converts this one type of power into the one or more types of powerrequired by the physical storage device, and outputs the converted oneor more types of power to the physical storage device. Further, thevoltage level of the one type of power from the main power supply lineis set to a value equal to or higher than the highest voltage level ofthe one or more types of power required by the physical storage devices.

In one embodiment, a plurality of storage device packs connected to amotherboard comprise different types of storage device packs, comprisingfirst and second types. A storage device pack of the first type has amultiple-power-supply type physical storage device requiring the supplyof a plurality of types of power, each with a prescribed voltage level,and a power conversion circuit which converts a single type of powerfrom the main power supply line into a plurality of types of powerrequired by the multiple-power-supply type physical storage device andinputs these into the multiple-power-supply type physical storagedevice. A storage device pack of the second type has asingle-power-supply type physical storage device requiring the supply ofa single type of power with a prescribed voltage level, and a powerconversion circuit which converts a single type of power from the mainpower supply line into the single type of power required by thesingle-power-supply type physical storage device and inputs this to thesingle-power-supply type physical storage device. Each type of storagedevice pack is such that connection is possible to any of a plurality ofpack connection sites on the motherboard.

In one embodiment, in the above second type of storage device pack, thesingle-power-supply type physical storage device has a plurality ofpower supply input terminals, and the single type of power output fromthe power conversion circuit is input to the physical storage device viathe above plurality of power supply input terminals.

In one embodiment, the plurality of storage device packs connected tothe motherboard comprise different types of storage device packs,comprising first and second types. A storage device pack of the firsttype has a first type physical storage device which requires the supplyof a first power type having a first voltage level, and a powerconversion circuit which converts the single type of power from the mainpower supply line into the first power type required by the first typephysical storage device and inputs this to the first type physicalstorage device. A storage device pack of the second type has a secondtype physical storage device which requires the supply of a second powertype having a second voltage level different from the first voltagelevel, and a power conversion circuit which converts the single type ofpower from the main power supply line into the second power typerequired by the second type physical storage device, and inputs this tothe second type physical storage device. Each of the types of storagedevice pack can be connected to any of the plurality of pack connectionsites on the motherboard.

In one embodiment, each of the plurality of pack connection sites on themotherboard has a U-turn power supply line which receives one or moretypes of power output from the power conversion circuit within a storagedevice pack, and again inputs this power to the storage device pack. Atleast one among the above plurality of storage device packs is apower-returning type storage device pack. This power-returning typestorage device pack further has a return power supply line to return oneor more types of power output from the power conversion circuit to theabove U-turn power supply line, and an input power supply line for inputto the physical storage device of the above one or more types of powerre-input from the U-turn power supply line. Also, a power-returning typestorage device pack can be connected to any of the plurality of packconnection sites on the motherboard.

In one embodiment, the above power-returning type storage device packhas a canister which accommodates the physical storage device and thepower conversion circuit. A main connector and auxiliary connector areprovided on the outer face of this canister. The main connector has apower supply terminal which functions as the above input power supplyline, and a data transfer terminal for connection of a data transferpath to the physical storage device. The auxiliary connector has a mainpower supply terminal for connection of the main power supply line tothe power conversion circuit, and a return power supply terminal forconnection of the above return power supply line to the U-turn powersupply line. And, in the canister, the physical storage device ispositioned in proximity to the main connector and is directly connectedto the main connector.

In one embodiment, the data transfer path of the motherboard forms aprescribed first data transfer interface. The plurality of storagedevice packs connected to the motherboard comprise different types ofstorage device packs, comprising first and second types. A first type ofstorage device pack has a first type of physical storage device havingthe above first data transfer interface, and a power conversion circuitwhich converts the single type of power from the main power supply lineinto the power required by the first type of physical storage device,and inputs this to the first type of physical storage device. On theother hand, a second type of storage device pack has a second type ofphysical storage device, having a second data transfer interfacediffering from the above first data transfer interface; a data transferinterface conversion circuit, which converts the above first datatransfer interface of the motherboard data transfer path into the seconddata transfer interface of the second type of physical storage deviceand supplies this to the second type of physical storage device; and, apower conversion circuit, which converts the single type of power fromthe main power supply line into the power required by the second type ofphysical storage device and by the data transfer interface conversioncircuit, and inputs these to the second type of physical storage deviceand to the data transfer interface conversion circuit respectively.Also, each of the types of storage device pack can be connected to anyof the plurality of pack connection sites on the motherboard.

In one embodiment, a power supply control circuit which individuallyturns on and off each of the power conversion circuits within theplurality of storage device packs is further provided.

In one embodiment, a power supply control circuit which individuallycontrols the output voltage levels of the power conversion circuitswithin the plurality of storage device packs according to the powersupply voltage levels required by the respective physical storagedevices within the plurality of storage device packs is furtherprovided.

By means of one embodiment of this invention, the power which can besupplied to the HDD units installed in a storage system can beincreased.

By means of one embodiment of this invention, a plurality of types ofHDD units with different power supply specifications can be installed inthe same storage system.

By means of embodiment of this invention, a plurality of types of HDDunits with different interface specifications can be installed in thesame storage system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing in summary the overall configurationof an aspect of a storage system according to this invention;

FIG. 2 is a block diagram showing an example of the specific internalconfiguration of an HDD pack 33, and a specific example of a method ofsupply of power from an AC/DC power supply circuit 29 to an HDD pack 33;

FIG. 3 shows in summary an example of the arrangement of internalcomponents in the HDD pack 33 shown in FIG. 2;

FIG. 4 is a block diagram showing another example of the specificinternal configuration of an HDD pack 33;

FIG. 5 shows in summary an example of the arrangement of internalcomponents in an HDD pack 33 in which is installed thesingle-power-supply type HDD unit 131 or 133 shown in FIG. 4;

FIG. 6 is a block diagram showing an example of another specificinternal configuration of an HDD pack 33, and showing still anotherspecific example of a method of supply of power to an HDD pack 33;

FIG. 7 shows in summary the arrangement of internal components in theHDD pack 33 shown in FIG. 6;

FIG. 8 shows an external view of the HDD pack 33 shown in FIG. 6;

FIG. 9 is a block diagram showing still another specific example of theinternal configuration of an HDD pack 33, and still another specificexample of a method of supply of power to an HDD pack 33;

FIG. 10 shows in summary the arrangement of internal components in anHDD pack 33 in which is mounted the SATA-specification HDD unit 185 or187 shown in FIG. 9;

FIG. 11 is a block diagram showing still another specific example of amethod of supply of power to an HDD pack 33; and, FIG. 12 is a blockdiagram showing still another specific example of the internalconfiguration of an HDD pack 33, and still another specific example of amethod of supply of power to an HDD pack 33.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows in summary the overall configuration of one aspect of astorage system according to this invention.

The storage system 20 shown in FIG. 1 comprises one or more channeladapters (CHA) 21, one or more disk adapters (DKA) 22, one or more cachememories (CACHE) 23, one or more shared memories (SM) 24, one or morecommon paths 25, a plurality of physical storage devices (that is,storage apparatus) 26, one or more connection control circuits 27, oneor more motherboards 28, and one or more main power supply devices 29.As the physical storage devices 26, hard disk drives, nonvolatilesemiconductor memory, or other types of devices can be employed, buttypically hard disk drives (hereafter abbreviated “HDDs”) are used. Inthe following explanation also, it is assumed that HDDs are employed.

The channel adapter 21, disk adapter 22, cache memory 23 and sharedmemory 24 are interconnected by the common path 25. The common path 25may be made twofold redundant (or multiple redundant) in anticipation offaults in the common path 25. The channel adapter 21 is connected by theconnection line 11 to one or more host computers 10 or to anotherstorage system (not shown). The channel adapter 21 controls datatransfer between the host computer 10 or other storage system and thecache memory 23. The disk adapter 22 controls data transfer between thecache memory 23 and HDDs 26. The cache memory 23 is memory used totemporarily hold data received from a host computer 10 or other storagesystem or data read from HDDs 26. The shared memory 24 is memory sharedby all the channel adapters 21 and all the disk adapters 22 in thestorage system 20. The shared memory 24 holds various information usedby the channel adapter 21 and disk adapter 22 for control andmanagement.

A motherboard 28 is an electrical circuit board comprising a wiringnetwork for data transfer for the HDDs 26 and a wiring network for powersupply. On each motherboard 28 is mounted two (or more) connectioncontrol circuits 27 which can be mutually substituted for a plurality ofHDDs 26. Each of the two connection control circuits 27 on eachmotherboard 28 connects, on that motherboard 28, a plurality of HDDs 26with two disk adapters 22 for which substitution is possible, to enablecommunication; as these connection control circuits 27, for example, afiber channel switch or a port bypass circuit or similar may beemployed. Each of the connection control circuits 27 and a plurality ofHDDs 26 are electrically connected via a wiring network on each of themotherboards 28. Also, each of the connection control circuits 27 andeach of the disk adapters 22 are electrically connected via, forexample, a multiwire cable. Data transfer is performed between aplurality of HDDs 26 and each of the disk adapters 22 via each of theconnection control circuits 27. By means of a (twofold) redundantconfiguration of the set of connection control circuit 27 and diskadapter 22 on each motherboard 28, safety can be improved inanticipation of malfunctions. As is explained in detail below, each HDD26 is accommodated in a canister (that is, housing) which can beattached to and removed from a motherboard 28; the pack of an HDD 26accommodated in such a canister or housing may be called an “HDD pack”or an “HDD housing”. In the following explanation, the term “HDD pack”is employed.

The reference numbers 31A, 31B, 31C each indicate groups of HDDs 26conforming to the RAID principle which are called parity groups (orerror collection groups), conforming to the RAID principle. Two or moreHDDs 26 belonging to the same parity group 31A, 31B or 31C are installedon different motherboards, and even if one of the HDDs 26 malfunctions,the data of the remaining HDD 26 stores redundant data enablingrestoration of the data of the malfunctioning HDD 26. It is desirablethat two or more HDDs 26 belonging to the same parity group 31A, 31B or31C have exactly the same storage capacity, and from this standpoint,normally the same model of HDD from the same manufacturer are combined;hence the electric power specifications and data transfer interface arealso the same.

The power supply system of this storage system 20 has one or more AC/DCpower supply circuits 29; each AC/DC power supply circuit 29 receives ACpower from an external AC power supply (for example, a commercial 200V_AC power supply) 30, converts this into DC power at a prescribedvoltage (for example, 56 V, 48 V, 24 V, or 12 V), and supplies this tothe plurality of HDD packs 33 and other circuits on the motherboard 28.Each AC/DC power supply circuit 29 is connected to a plurality of HDDpacks 33 on each motherboard 28 via a wiring network for power supply oneach motherboard 28. In anticipation of power outages, twofold redundant(or multiple redundant) AC power supplies 30, mutual substitution ofwhich is possible, are used. Each AC power supply 30 is connected totwofold redundant or multiple-redundant AC/DC power supply circuits 29,mutual substitution of which is possible. In the example shown, eachAC/DC power supply circuit 29 is shared among a plurality ofmotherboards 28, but as a modified form, each motherboard 28 maycomprise one or more dedicated AC/DC power supply circuits.

FIG. 2 shows an example of the specific internal configuration of an HDDpack 33, and an example of the power supply wiring from an AC/DC powersupply circuit 29 to an HDD pack 33. In FIG. 2, the data transfer wiringis omitted. FIG. 3 shows in summary the arrangement of internalcomponents of the HDD pack 33 shown in FIG. 2. In FIG. 3, the wiring fordata transfer is shown in an extremely simplified manner.

As shown in FIG. 2, a plurality of HDD packs 33 are connected to onemotherboard 28. The motherboard 28 has a plurality of HDD packconnection sites for connection to HDD packs 33, and a plurality of HDDpacks 33 are connected to these HDD pack connection sites. Themotherboard 28 and plurality of HDD packs 33 are accommodated within thecasing 105 of the storage system main body. Each HDD pack 33 isconnected to the redundantly configured power supply lines 103A and 103Bvia the motherboard 28. The power supply line 103A is supplied with DCpower at the same voltage level (that is, voltage value) as an AC/DCpower supply circuit 29A to enable mutual substitution. The other powersupply line 103B is also supplied with DC power at the same voltagelevel from the AC/DC power supply circuit 29B, configured with twofoldor higher redundancy. At least one among the redundantly configuredpower supply lines, for example power supply line 103B, is alsoconnected to a battery portion 101 as a backup power supply inanticipation of AC power supply outages. The DC voltage level suppliedto each HDD pack 33 by the redundantly configured power supply lines103A and 103B is a single voltage level. This single power supplyvoltage level is selected so as not to be lower than any of theplurality of power supply voltage levels (for example, 12 V and 5 V)required by any of the HDD units 107, 108 within any of the HDD packs33, and preferably to be a much higher level (for example, 56 V_DC or 48V_DC) which does not exceed a prescribed safety standard (for example,an upper limit of 60 V).

Each HDD pack 33 has one HDD unit 107 or 108 and one DC/DC converter109, which are interconnected. The HDD unit 107 is amultiple-power-supply type, requiring the supply of all of the pluralityof types of DC power (power supply lines 113, 115) with differentvoltage levels (for example, 12 V and 5 V). On the other hand, the HDDunit 108 is the single-power-supply type, which operates under thesupply of power at only a single voltage level (for example, 12 V)(power supply line 113). A single-power-supply type HDD unit 108 canincorporate a power conversion circuit which converts the power supplyvoltage at a single voltage supplied by the motherboard 28 into theplurality of power supply voltages required by internal circuitcomponents (for example, the comparatively high voltage used to drivemagnetic disks, the comparatively low voltage used by logic circuitsperforming control and data processing, and similar), and supplies theseto the respective internal circuit components. As explained above inrelation to the prior art, in each HDD unit 107 or 108 the group ofcomponents necessary to function as an HDD (for example, the magneticdisks, read/write heads, power transmission mechanisms and othermechanical components, the motors and other electromechanical componentsneeded to drive the former, and the driver circuits for theelectromechanical components, logic circuits for data processing,microprocessors, and other electrical circuit components) areindivisibly integrated and fixed in a single casing. Each HDD unit 107or 108 can function independently as an HDD, and hence in a conventionalstorage system, the HDD unit 107 or 108 is itself directly connected tothe motherboard. However, in the example shown in FIG. 2, the HDD unit107, 108 is not itself directly connected, but a HDD pack 33 which is acombination of an HDD unit 107 or 108 and a DC/DC converter 109 isdirection connected to the motherboard 28.

As shown in FIG. 3, one HDD unit 107 or 108 and a DC/DC converter 109are accommodated in one canister 117, the entirety of which forms asingle HDD pack 33. On the outer face of the canister 117 of the HDDpack 33 is provided a connector 119A having a prescribed number of powersupply terminals and data transfer terminals. This connector 119A isconnected to the connector 119B with the same specifications provided onthe motherboard 28; by this means, the twofold-redundant power supplylines 103A, 103B on the motherboard 28 are connected to the inputterminals of the DC/DC converter 109 within the HDD pack 33, andmoreover the twofold-redundant data transfer paths 123A, 123B on themotherboard 28 are connected to the terminals on one side of thetwofold-redundant data transfer paths 125A, 125B within the HDD pack 33.The HDD unit 107 or 108 in the HDD pack 33 has, on the casing outersurface, a connector 121A having the number of power supply terminalsand data transfer terminals conforming to the data transfer interfacespecifications (for example, FC) adopted by the HDD. This connector 121Ais connected to a connector 121B with the same specifications within theHDD pack 33, and by this means the output power supply lines 113, 115 ofthe DC/DC converter 109 are connected to the power supply inputterminals of the HDD unit 107 or 108, and moreover the other-endterminals of the twofold-redundant data transfer paths 125A, 125B areconnected to the data transfer terminals of the HDD unit 107 or 108.

The DC/DC converter 109 within the HDD pack 33 converts the DC power atthe single voltage level (for example, 48 V) supplied by thetwofold-redundant power supply lines 103A, 103B into the plurality oftypes of DC power with the plurality of voltage levels (for example, 12V and 5 V) required by all the HDD units 107 and 108, and supplies theseto the HDD unit 107 via the power supply lines 113, 115. As shown inFIG. 2 and FIG. 3, the DC/DC converter 109 has an input selector 110 anda step-down converter 111. The input selector 110 uses the difference inthe voltage step-down of one diode and two diodes in series to selectone among the twofold-redundant power supply lines 103A, 103B andconnect this to the step-down converter 111. For example, when both thetwofold-redundant power supply lines 103A, 103B are operatingeffectively, the uppermost input selector 110 in FIG. 2 connects thefirst power supply line 103A, for which the diode voltage step-down issmaller, to the step-down converter 111, and the second input selector110 from the top connects the second power supply line 103B to thestep-down converter 111. In this way, when both the twofold-redundantpower supply lines 103A, 103B are operating effectively, substantiallyhalf of the plurality of HDD packs 33 select the first power supply line103A, and substantially the other half select the second power supplyline 103B. By this means, the loads on the twofold-redundant powersupply lines 103A and 103B are balanced. When one of thetwofold-redundant power supply lines 103A and 103B undergoes a poweroutage, all the input selectors 110 select the normally operating powersupply line.

As shown in FIG. 2 and FIG. 3, the step-down converters 111 within theDC/DC converters 109 convert one type of DC power at a single voltagelevel (for example, 48 V) from the power supply line 103A or 103Bselected by the input selector 110 into the plurality of types of DCpower at different voltage levels (for example, 12 V and 5 V) requiredby all the HDD units 107 and 108, and output these to the power supplylines 113, 115. As a step-down converter 111, for example, a powerconversion circuit of the type which performs voltage step-down throughon/off switching of the load circuit, such as for example adirect-current chopper circuit, can be used.

As explained above, the two HDD units 107 shown in the top of FIG. 2 areof the multiple-power-supply type, requiring supply of all the pluralityof types of DC power with different voltage levels (for example, 12 Vand 5 V) output from the DC/DC converter 109. On the other hand, the HDDunit 108 shown in the bottom of the figure is of the single-power-supplytype, which operates when supplied with only one type among a pluralityof types of DC power (for example, 12 V_DC power). Thesingle-power-supply type HDD unit 108 is connected to only the one powervoltage level required by the HDD unit 108 among the output terminals ofthe DC/DC converter 109, for example, the 12 V_DC power supply line 113.In this way, if the HDD units 107 and 108 are of a type which canoperate on any of the plurality of types of DC power 113, 115 output bythe DC/DC converter 109, then the HDD units 107 and 108 can be installedon the HDD pack 33 which are installed/connected to the same motherboard28.

Here, it is assumed that 12 V_DC and 5 V_DC are supplied to themultiple-power-supply type HDD units 107, and that 12 V_DC is suppliedto the single-power-supply type HDD unit 108. It is further assumed thatthe internal power consumption of both types of HDD units 107 and 108 isthe same. And, it is assumed that a single-power-supply type HDD unit108 incorporates a power conversion circuit to convert the 12 V_DCsupplied from outside into the 5 V_DC required by the internal logiccircuit components, and that the efficiency of this power conversioncircuit is 80%. In this case, compared with a multiple-power-supply typeHDD unit 107, the power supply current for logic circuit componentsflowing in the power supply terminals of the connector 121A of asingle-power-supply type HDD unit 108 is reduced by half due to theconversion of 12 V_DC to 5 V_DC. Consequently even if the powerconsumption of internal circuit components increases somewhat, it iseasy to stay within the allowable current for the power supply terminalsof the connector 121A.

In the configuration example shown in FIG. 2 and FIG. 3, compared with aconventional configuration in which the HDD units 107 or 108 aredirectly connected to the motherboard, the power supply current suppliedfrom the motherboard 28 to the HDD units 107 is reduced. Hence impedanceof the power transmission path from the motherboard 28 to the DC/DCconverter 109 and to the DC/DC converters existing in HDD units 108 andsimilar, and the power supply noise arising from HDD ripple currentsgenerated due to the conversion, are reduced.

FIG. 4 shows an example of another specific internal configuration of anHDD pack 33. In FIG. 4, the data transfer wiring is omitted.

In the configuration example of FIG. 4, the three or more types of HDDunits 107, 131 and 133 are installed in HDD packs 33 which areconnected/installed on the same motherboards 28. One type of HDD unit107 is a multiple-power-supply type, requiring DC power (power supplylines 113 and 115) at for example two voltage levels (for example, 12V_DC and 5 V_DC). Another type of HDD unit 131 is a single-power-supplytype, operating on DC power (power supply line 139) at a voltage leveldifferent from those above (for example, 24 V). Still another type ofHDD unit 133 is a single-power-supply type, requiring DC power (powersupply line 145) at still another voltage level (for example, 48 V). Thepower supply voltage levels required by the single-power-supply types ofHDD unit 131 and 133 are equal to or, preferably, higher than (forexample, 24 V_DC, 48 V_DC, or similar) the highest value (for example 12V_DC) of the plurality of power supply voltage levels required by theinternal circuit components of the HDD units 131 and 133 (for example,12 V_DC and 5 V_DC). In HDD packs 33 accommodating such different typesof HDD units 107,131 and 133, different types of DC/DC converters109,135 and 141 are installed which respectively generate the differentvoltage levels (for example, 12 V, 5 V, 24 V, 48 V) required by the HDDunits 107,131,133 from the DC power at the single high voltage levelfrom the motherboard 28 (for example, 48 V). The differences in thesetypes of DC/DC converters 109, 135 and 141 are mainly the differences inoutput voltages of the step-down converters 111, 137, 143 installedtherein. That is, the step-down converter 111 converts the DC power atthe single high voltage level from the motherboard 28 (for example, 56 Vor 48 V, or similar) into DC power at the two voltage levels required bythe corresponding HDD unit 107 (for example, 12 V_DC and 5 V_DC), andoutputs this to the power supply lines 113 and 115. Another step-downconverter 137 converts the DC power at the single high voltage levelfrom the motherboard 28 (for example, 56 V or 48 V) into DC power at thesingle voltage level required by the corresponding HDD unit 131 (forexample, 24 V), and outputs this to the power supply line 139. And, theother step-down converter 143 converts the DC power at the single highvoltage level from the motherboard 28 (for example, 56 V or 48 V) intoDC power at the single voltage level required by the corresponding HDDunit 133 (for example, 48 V), and outputs this to the power supply line145. When the power supply voltage level from the motherboard 28 and thepower supply voltage level required by an HDD unit are equal (forexample, when both are 48 V), the step-down converter may be eliminated;or, in place of a step-down converter, a circuit to stabilize thevoltage level output to the HDD unit (for example, a circuit whichemploys a large-capacity capacitor to suppress fluctuations in theoutput voltage level arising from fluctuations in the load current ofthe HDD unit) may be used.

FIG. 5 shows in summary an example of arrangement of internal componentsof an HDD pack 33 in which is installed a single-power-supply type HDDunit 131 or 133, shown in FIG. 4.

As shown in FIG. 5, a case is assumed in which a connector 121A havingphysical specifications similar to those of the multiple-power-supplytype HDD units 107 or 108 shown in FIG. 3 is used in thesingle-power-supply type HDD unit 131 or 133. This connector 121A isassumed to conform for example to FC specifications, and has four powersupply terminals. In such a case, in the multiple-power-supply type HDDunits 107 or 108 shown in FIG. 3, two of the four power supply terminalsare allocated to the 12 V_DC power 113, and the remaining two areallocated to the 5 V_DC power 115; whereas in the single-power-supplytype HDD units 131 or 133 shown in FIG. 5, all four of the power supplyterminals can be used to supply power 139 or 145 at a single highvoltage level (for example, 24 V, 48 V, or similar). By this means, thepower which can be supplied to the HDD unit 131 or 133 is increased.

FIG. 6 shows another example of a specific interior configuration of anHDD pack 33, and still another example of a method of supply of power toan HDD pack 33. In FIG. 6, the wiring for data transfer is omitted. FIG.7 shows in summary the arrangement of internal components of the HDDpack 33 shown in FIG. 6. In FIG. 7, the wiring for data transfer isshown in an extremely simplified manner. FIG. 8 shows an external viewof the HDD pack 33 shown in FIG. 6.

In the configuration example of FIG. 6, after the power output from thestep-down converter 111, 164 or 167 within each HDD pack 33 is oncereturned to the motherboard 28, it is supplied to the HDD units 107, 163or 165 within the HDD packs 33 from the motherboard 28. That is, U-turnpower supply lines 151, 153 are provided on the motherboard 28corresponding to each HDD pack 33. Within each HDD pack 33 there existsreturn power supply lines 155, 157; these return the power output from astep-down converter 111, 164 or 167 to the U-turn power supply lines151, 153 of the motherboard 28. The U-turn power supply lines 151, 153input the returned power to the power supply input lines 159, 161 of theHDD units 107, 163 or 165 within each HDD pack 33.

As shown in FIG. 7 and FIG. 8, the connector 121A of the HDD units 107,163 or 165 and the power supply connector 171A are provided on the outerface of the canister 117 of the HDD pack 33; these connectors 121A and171A are connected to the corresponding connectors 119B and 171B on themotherboard. The power output by the DC/DC converter 109, 164 or 167within the HDD pack 33 passes through the power supply connector 171A,is returned to the U-turn power supply lines 151, 153 on the motherboard28, and is input from the U-turn power supply lines 151, 153 to thepower supply terminals (power supply lines) 159, 161 of the connector121A of the HDD unit 107, 163 or 165. As shown in the figure, becausethe connector 121A of the HDD unit 107, 163 or 165 is directly connectedto the connector 119B on the motherboard 28, the distance between thetwo is very short, and there is no circuitry or wiring interveningtherebetween. As a result, power can be supplied to the HDD unit 107,163 or 165 without degradation of the waveform quality of the high-speeddata signal.

Referring again to FIG. 6, the two HDD units 107 shown in the top of thefigure are multiple-power-supply type units requiring, for example, 12V_DC power and 5 V_DC power. The HDD unit 163 shown second from thebottom is a single-power-supply type unit requiring a single type ofsupplied power at a higher voltage level (for example, 24 V_DC) than thepower supplied to the above HDD units 107. And the HDD unit 165 shown atthe bottom is a single-power-supply type unit requiring a single type ofpower to be supplied, at for example another voltage level (for example,48 V_DC). Here, a case is imagined in which the HDD units 107, 163 and165 all have a connector 121A with the same specifications. Thisconnector 121A is assumed to have four power supply terminals conformingto, for example, FC specifications. In this case, in each of the two HDDpacks 33 shown at the top, the step-down converter 111 outputs two typesof power, for example at 12 V_DC and 5 V_DC, required by themultiple-power-supply type HDD units 107. These two types of power areinput, via the single U-turn power supply lines 151 and 153 on themotherboard 28, to the two power supply terminals for 12 V_DC and thetwo power supply terminals for 5 V_DC in the connector 121A of the HDDunits 107. In the HDD pack 33 shown second from the bottom, thestep-down converter 164 outputs a single type of power, for example 24V_DC, required by the single-power-supply type HDD unit 163. This singletype of power is input, via the U-turn power supply line 153 on themotherboard 28, to two of the four power supply terminals in theconnector 121A of the HDD unit 163. And, in the HDD pack 33 shown at thebottom, the step-down converter 167 outputs a single type of power, forexample 48 V_DC, required by the single-power-supply type HDD unit 165.This single type of power is input, via both the U-turn power supplylines 151 and 153 on the motherboard 28, to all four of the power supplyterminals in the connector 121A of the HDD unit 165. By means of aconfiguration in which one type of power is supplied using all of theplurality of power supply terminals of the connector 121A of the HDDunit 165, as in the case of the lowermost HDD pack 33, higher power caneasily be supplied compared with a configuration in which only a portionof the power supply terminals is used for the supply of one type ofpower, as in the case of the other HDD packs 33.

The types and numbers of the HDD units 107, 163 and 165 shown in FIG. 6are no more than simple examples for purposes of explanation. Accordingto the configuration example shown in FIG. 6, an arbitrary number of theHDD units 107, 163 and 165 of different types and requiring DC power atdifferent voltage levels can be installed at arbitrary positions on thesame motherboard 28. Moreover, as explained above, there is littledegradation of the waveform quality of high-speed data signals.

FIG. 9 shows another example of a specific internal configuration of anHDD pack 33, and still another example of a method of supplying power toan HDD pack 33. In FIG. 9, the wiring for data transfer is shown in anextremely simplified manner. FIG. 10 shows in summary the arrangement ofinternal components of an HDD pack 33 in which is installed theSATA-specification HDD unit 185 or 187 shown in FIG. 9.

In the configuration example of FIG. 9, the different types of HDD units107, 181, 185 and 187 having different data transfer interfacespecifications are installed on the same motherboard 28. For example,the HDD units 107 and 181 shown in the top of the figure conform to theFC (fiber channel) interface specification. The uppermost HDD unit 107is a multiple-power-supply type unit requiring the supply of power at aplurality of voltage levels, for example 12 V_DC and 5 V_DC, and thesecond HDD unit 181 is a single-power-supply type unit requiring thesupply of power at a single voltage level, for example 24 V_DC. The HDDunits 185 and 187 shown in the bottom are SATA(serial-ATA)-specification units. The HDD unit 185 which is second fromthe bottom is a multiple-power-supply type unit requiring the supply ofpower at a plurality of voltage levels, for example 12 V_DC and 5 V_DC,and the lowermost HDD unit 187 is a single-power-supply type unitrequiring the supply of power at a single voltage level, for example 24V_DC. The configuration of an HDD pack 33 in which is installed anFC-specification HDD unit 107 or 181 is as previously explained withreference to FIG. 6 through FIG. 8.

As shown in FIG. 9 and FIG. 10, an HDD pack 33 in which is installed aSATA-specification HDD unit 185 or 187 is provided with an FC/SATAconverter 195 which performs conversion from the FC-specification datatransfer interface on the motherboard side (data transfer paths 123A,123B) to the SATA-specification data transfer interface on the HDD side(data transfer path 201), as well as the reverse conversion. A DC/DCconverter 111 or 189 within an HDD pack 33 not only supplies power tothe HDD unit 185 or 187 (the power supply lines 113 and 115 or 191), butalso supplies power (for example, 5 V_DC) to the FC/SATA converter 195.In the example shown, the FC/SATA converter 195 converts theFC-specification data transfer paths 123A, 123B for two ports into theSATA-specification data transfer path 201 for one port. As amodification, the FC/SATA converter 195 may also transfer one port'sworth of the FC-specification data transfer path 123A or 123B into oneport's worth of the SATA-specification data transfer path 201. However,as shown in the figure, an FC/SATA converter 195 which supports theFC-specification data transfer paths 123A, 123B of two ports affordshigher safety with respect to interface faults than support for a singleport.

In FIG. 9 the reference numbers 200A, 200B refer to twofold-redundantHDD control boards provided on the motherboard 28, and each of which cansubstitute for the other. The HDD control boards 200A, 200B respectivelyhave FC control circuits 213A, 213B. The FC control circuits 213A, 213Bare respectively connected to the twofold-redundant connection controlcircuits 27A and 27B on the motherboard 28 (for example, fiber channelswitching circuits or port bypass circuits, or similar), and, via thedata transfer paths 219A, 219B, with the twofold-redundant channeladapters 21 shown in FIG. 1 intervening, to the connection controlcircuits 27A, 27B. The FC control circuits 213A, 213B control theconnection control circuits 27A, 27B, and via the connection controlcircuits 27A, 27B, exchange data with all of the HDD packs 33 on themotherboard 28.

The types and numbers of the HDD units 107, 181, 185 and 187 shown inFIG. 9 are no more than simple examples for purposes of explanation.According to the configuration example shown in FIG. 9, a plurality oftypes of HDD unit, with different data transfer interfaces such asFC-specification and SATA-specification interfaces and also withdifferent power supply voltage levels, can be installed on the samemotherboard. The principle of this configuration example can be appliednot only to cases in which HDD units with different interfacespecifications are used together, but also to cases in which only HDDunits with one interface specification are used. As was explainedreferring to FIG. 1, normally two or more HDDs 26 belonging to the sameparity group are the same with respect to power supply specificationsand data transfer interface specifications. On the other hand, it ispossible for power supply specifications or for data transfer interfacespecifications to differ between different parity groups. In this case,in the configuration shown in FIG. 9, the power supply specification ordata transfer specification can be made different for each parity group.

FIG. 11 shows still another example of a method of supplying power toHDD packs 33. In FIG. 11, the AC/DC power supply circuit has beenomitted.

In the configuration example of FIG. 11, the twofold-redundant HDDcontrol boards 211A, 211B, each of which can be substituted for theother, are provided on the motherboard 28. The HDD control boards 211A,211B respectively have FC control circuits 213A, 213B and power supplycontrol circuits 215A, 215B. As already explained referring to FIG. 9,the FC control circuits 213A, 213B control the twofold-redundantconnection control circuits 27A, 27B on the motherboard 28, and throughthese connection control circuits 27A, 27B, exchange data with all theHDD packs 33 on the motherboard 28. The power supply control circuits215A, 215B monitor the state of the DC power supply wiring on themotherboard 28, and by outputting control signals 217A, 217Bindividually turn on and off the DC/DC converters 109 (step-downconverters 111, 183, 189) within all of the HDD packs 33 on themotherboard 28. The configuration of other portions of the motherboard28 and of the HDD packs 33 are similar to the configuration example ofFIG. 9 explained above.

In the configuration example of FIG. 11, the control functions of thepower supply control circuits 215A, 215B can be utilized as follows. Forexample, when inserting or removing a live wire of an HDD pack 33 (whenattaching or removing to or from the motherboard 28 an HDD pack 33 in astate in which the DC power supply lines 103A, 103B are live), the DC/DCconverter 109 within the HDD pack 33 can be put into the stopped statein advance by means of the power supply control circuits 215A, 215B. Inthis way, the danger of rush currents entering an HDD unit 107, 181, 185or 187 upon insertion or removal of a live wire can be avoided. Also,when for example an HDD pack 33 is currently being used, the supply ofpower to the HDD pack 33 can be halted. By this means, power consumptioncan be controlled according to the state of use of the HDD, and wastefulpower consumption can be decreased. Also, there are cases in which thetotal time over which consecutive use is possible is specified to beshorter for the SATA-specification HDD units 185, 187 than for theFC-specification HDD units 107, 181. In such cases, for example duringstandby, the power supply control circuits 215A, 215B can be used tohalt the supply of power to SATA-specification HDD units 185, 187. Bythis means, the effective time of use of SATA-specification HDD units185, 187 can be extended, and brought closer to the lifetime ofFC-specification HDD units 107, 181. Also, in order to perform pairingor mirroring of logical volumes according to the RAID principle,FC-specification HDD units 107, 181 can be allocated as primary volumesfor online access, with SATA-specification HDD units 185, 187 allocatedas secondary volumes which are copies of the primary volumes. In thiscase, for example during online operations, power is supplied to theFC-specification HDD units 107,181 allocated as primary volumes, but thepower supply to the SATA-specification HDD units 185, 187 allocated assecondary volumes can be stopped except when writing copied data, so asto extend the lifetime.

Also, SATA-specification HDD units 185, 187 can be allocated to storagedevices for backup of FC-specification HDD units 107, 181. In this case,the power supply to the SATA-specification HDD units 185, 187 can bestopped except during backup operation. By this means, inexpensiveSATA-specification HDD units 185, 187 employed as storage devices forbackup can be used with approximately the same lifetime asFC-specification HDD units 107, 181. Moreover, power consumption can beeffectively reduced.

FIG. 12 shows still another example of a specific internal configurationof an HDD pack 33, and still another specific example of a method ofsupplying power to an HDD pack 33. In FIG. 12, the AC/DC power supplycircuit is omitted.

In the configuration example of FIG. 12, the specifications of the HDDunits 107, 181, 185 and 187 are similar to those of the configurationexamples in FIG. 9 and FIG. 11. In the configuration example of FIG. 12,the DC/DC converters 109 for these HDD units 107, 181, 185 and 187 aremounted on the motherboard 28. Hence the DC/DC converters 109 do notexist within the respective HDD packs 33. Consequently when replacingHDD packs 33, the DC/DC converters 109 are not also replaced, and inthis respect greater economy is achieved. Various arrangements of theDC/DC converters 109 on the motherboard 28 can be adopted. As oneexample of an arrangement, the DC/DC converters 109 are arranged inproximity to the installation positions of the corresponding HDD packs33. By this means, the transmission path from the DC/DC converter 109 tothe HDD pack 33 is made short, so that the effect of power supply noiseis minimal.

Also, twofold-redundant HDD control boards 221A, 221B are provided oneach motherboard 28. The HDD control boards 221A, 221 B have FC controlcircuits 213A, 213B and power supply control circuits 225A, 225B. Thefunctions of the FC control circuits 213A, 213B have already beenexplained. In addition to controlling the turning on and off of each ofthe DC/DC converters 109 as already explained, the power supply controlcircuits 225A, 225B also have functions to indicate to each DC/DCconverter 109 the power supply voltage levels required by each HDD pack33 by means of voltage control signals 223A, 223B, and to change theoutput voltage levels of the DC/DC converters 109 according to the HDDpacks 33. When the step-down converters in the DC/DC converters 109 areof the type which perform power conversion through switching, such as achopper circuit, as one method to control the output voltage level ofeach DC/DC converter 109, for example, the target voltage levelindicated by the voltage control signals 223A, 223B can be compared withthe output voltage level, and the switching duty ratio increased orreduced such that the difference disappears.

Through the above-described representative aspects of this invention, atleast the following advantageous results can be obtained.

(1) HDD units which operate at a single power supply voltage can beinstalled in a storage system.

(2) A plurality of HDD types, requiring different power supply voltages,can be installed together on the same motherboard.

(3) A plurality of HDD units requiring different power supply types canbe installed at arbitrary times at arbitrary positions on a motherboard.Hence the range of HDD units which can be selected for use in future canbe expanded.

(4) HDD units requiring a power supply voltage level of 12 V_DC orhigher, which is the highest power supply voltage level of HDD unitsgenerally adopted for use in the prior art, can be flexibly supported.By using a higher power supply voltage level than in the prior art, thepower supply current can be reduced compared with the prior art, andpower supply voltage stability is improved.

(5) Inexpensive SATA-specification HDD units can be installed on thesame motherboard together with FC-specification HDD units.

(6) When all the HDD units initially installed on a motherboard areFC-specification units, these FC-specification HDD units can be replacedin sequence with SATA-specification HDD units, so that ultimately allunits are replaced by SATA-specification HDD units.

(7) By individually controlling the turning on and off of the powersupplied to each HDD unit among the plurality of HDD units in thestorage system, for example, SATA-specification HDD units can be used assecondary storage devices for backup or mirroring of FC-specificationHDD units within the same system. By this means, the reliability of thestorage system is improved, and cost reductions are easily achieved.

(8) HDD units with different power supply specifications can be backedup by batteries at a single voltage level.

In the above, aspects of this invention have been explained; but theseaspects are no more than examples used to explain the invention, and thescope of the invention is not limited only to these aspects. Thisinvention can be implemented in various other modes without deviatingfrom the gist of the invention.

1. A storage system, which can be connected to a host computer, having:a plurality of storage devices which store data from said host; aplurality of housings in which said plurality of storage devices aremounted; and a plurality of first power supplies which supply a voltageto said plurality of storage devices, and wherein at least one of saidplurality of housings has a first voltage converter which receives powerhaving a first voltage value from said first power supply, converts saidfirst voltage value into a second voltage value different from saidfirst voltage value, and supplies power having a single voltage value tosaid storage device.